Rock drill



Q I 65 r i 'luly 1941- w. AMORRISQN ETAL 2 5 ROCK DRILL Filed Nov. 18, 1959 1 V 7 7: 45 S a? g; 540

\i gy I INVEN TOR With/21.4. [unison and THEIR ATTORNEY Patented July 8,1941

STATES PATENT GFICE noon DRILL Application November 18, 1939, Serial No. 305,116

' 7 Claims. (01. 121-18) This invention relates to rock drills, and more particularly to rock drills of the fluid actuated reciprocatory piston type.

One object of the invention is to minimize the pressure 'fluid consumption for actuating the rock drill.

Anotherobject is to Vary the stroke characteristics of the drill piston in accordance with the variations in hardness of the rock being drilled.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawing accompanying this specification and in which similar reference numerals refer to similar parts,

Figure 1 is an elevation, partly in section, of a rock drill constructed in accordance with the practice of the invention and showing the reciprocatory piston in one of the limiting positions, and

Figure 2 is a view similar to Figure 1 showing the piston in another limiting position.

Referring more particularly to the drawing, 20 designates, in general, a rock drill comprising a cylinder 2! having a piston chamber 22 to accommodate a reciprocatory piston 23.

A closure 24 is arranged in the rearward end of the cylinder 2|, to seal that end of the piston chamber 22, and at the front end of thecylinder is a front head 25 containing a bushing 26 to guide an extension 2'! of the piston 23.

The piston 23 is of the differential type having a reduced pressure surface 28 at its front end and a relatively large rear pressure surface 2s and, in accordance with the practice of the invention, pressure fluid is constantly supplied to the piston chamber forwardly of the piston to extreme front end of the piston chamber to assure a supply of pressure fluid beneath the piston 23 in the event that the piston assumes a position in which it blanks off the port 33.

The rear pressure surface 29 of the piston is subjected intermittently to pressure fluid for actuating the piston on its working stroke. The distribution of such pressure fluid is effected by valve mechanism, designated'in' its entirety by 34, arranged adjacent the rear end of the piston chamber andcomprising a valve chest 35 having bushings Stand 3'! inserted in its rearward and front ends, respectively, to define a valve chamber 38 which communicates with the rear end of the piston chamber 22 through an inlet passage N. J., assignors to 39. The bushings 35 and 31 have flanges 4% which seat against the ends of the valve chest 35.

The outer surface of the flange 30 of the bushing 31, in turn, serves as a seat for a flange 4| of the conduit 3! which communicates with the front end of the valve chamber 33 through a passage 42 extending through the flange 4i and the bushing '31. Similarly, the flange 40 of the bushing 36 serves as a seat for a flange 43 of a conduit 44 leading from a source of pressure fluid supply and communicating with the rear end of the valve chamber 38 through a port 45 in the bushing 36. V

The valve'chamber-iia contains a reciprocable valve 46 for controlling the admission of pressure fluid from the supply conduit 44 to the inlet passage 39 and also for controlling the exhaust of fluid from the rearwardend of the piston chamber 22, such exhaust taking place through the inlet passage 39 and the valve chamber 38 and through an atmospheric exhaust port 41 leading from the forward portion of the valve chamber 38 through the valve chest 35. The valve 46 has a bore48 extending entirely therethrough so that,

in the-struct1ire shown, pressure fluid may flow constantly from the supply conduit ifithrough the bore 48 into the conduit 3| and, therefore, into the front end of the piston chamber.

- Within the bore 38 is a bevelled shoulder 49 which, with the front end 58 of the valve, constitutes an actuating area that is constantly subjected to pressure fluid tending to throw the valve rezirwardly; The opposite end 5t of the valve is likewise constantly exposed to pressure fluid and this force is augmented by pressure fluid acting intermittently upon an actuating surface 52 on the rearward end of a flange 53 encircling the valve 46. A second flange 54 on the valve lies forwardly of the flange 53 to control'communication between the valve chamber and the inlet port 39, and in the wall of the valve 36 between theflanges 53 and 54 are radialports 55 through which pressure fluid flows fromthe'interior of the valve 66 to the inlet passage 39.

The pressure fluid acting against the actuating surface 52 for throwing the valve it forward. ly is conveyed thereto by a kicker passage 56 extending through the cylinder 2| and, in the present instance, a tube5'l. The kicker passages opens into the forward portion of the piston chamber "22fat a point rearwardly of the port 30 so that when the piston 23 moves to the forward end of the piston chamber it will blank ofif th e k icker passage 55, and during its rearward strokethe piston will again uncover the kickerpassage to admit pressure fluid to the actuating surface 52. g V V I Means are provided to vary the character of the ,blowof the piston 23 in accordance with variations in the hardness characteristics of the rock being drilled. To this end a needle valve 58 threadedly connected to the cylinder 2] is arranged in the kicker passage 55 to selectively restrict the flow of pressure fluid from the piston chamber 22 into the kicker passage and thus to the actuating surface 52. In order to also restrict the exhaust of pressure fluid from the kicker passage a second needle valve 59 is arranged in the picker passage 56 to control communication between said kicker passage and an exhaust passage 60 leading from the kicker passage, at a point rearwardly of the needle valve 58, to the piston chamber 22.

A second exhaust passage 6!, preferably arranged in the same transverse plane as the exhaust passage 68, leads from the piston chamber 22 to the atmosphere, and in the periphery of the piston '23 is an annular groove 63 to afford communication between the exhaust passages 55 and 6!.

The operation of the device is as follows: With the piston 23 in the rearward limiting position and the valve in the forward limiting position shown in Figure 1 pressure fluid flows through the ports 55 and the inlet passage 39 into the rear end of the piston chamber 22 and drives the piston forwardly on its working stroke.

As the piston approaches the front end of the piston chamber it will blank oh the kicker pasplane of the passages 60 and BI and the pressure fluid acting against the actuating surface 52 will then be exhausted to the atmosphere. The pressure fluid acting against the shoulder 49 and the end surface 59 of the valve 46 will then actuate the valve rearwardly and cut off, communication between pressure fluid supply and the inlet passage 39.

In the new position of the valve the inlet passage 39 will be communicated with the exhaust port 4'! so that the pressure fluid in the rearward end of the piston chamber will escape to the atmosphere. The pressure fluid acting against the pressure surf-ace 28 will then move the piston rearw-ardly to its initial position. During the rearward movement of the piston the portion of the piston lying forwardly of the annular groove 63 again covers the exhaust passage 60 and uncovers the kicker passage 56 to admit pressure fluid to the actuating surface 52 of the valve for again throwing the valve.

The described cycle of operations may be repeated indefinitely or as long as the nature of the work is such as to require a piston blow of the force which may be obtained with given settings of the needle valves 58 and 59, as for example when the needle valves are in position to permit of free communication between the kicker passage and the associated chambers and channels. When, however, rock of a different degree of hardness is encountered, as for instance rock in which best results may be obtained by heavy piston blows the needle valve 58 is adjusted to a position to partially restrict the admission of pressure fluid from the piston chamber 22 into the kicker passage 55. The pressure fluid will then pass relatively slowly into the kicker passage and to the actuating surface 52 so that the actuation of the valve 46 in a forwardly direction will be delayed somewhat. In'consequence, the piston 23 will be caused to travel its full nominal stroke rearwardly by the pressure fluid acting against the pressure surface 28 before the valve 46 is thrown into position to again effect the charging of the rear end of the piston chamber. The piston 23 will then travel its maximum distance on its working stroke and, therefore, deliver a comparatively heavy blow against the work.

In order to further assure this result the needle valve 59 may also be adjusted to a position in which it restricts the flow area between the kicker passage and the exhaust passage 60. When the needle valve 59 is thus positioned the pressure fluid exhausts from the actuating surface 52 relatively slowly so that the piston travels a longer distance downwardly before the pressure fluid acting against the shoulder 49 and the surface 50 of the valve may predominate over that acting against the surfaces 5| and 52. In this way the charging period of the rear end of the piston chamber will be somewhat extended and this fact, together with the long stroke of the piston 23, will assure a heavy blow against the work.

Whenever best drilling results may be obtained by the use of relatively light piston blows both of the needle valves may be adjusted to increase the flow areas between the kicker passage and the associated channels. The kicker passage and associated chambers will then be quickly charged after the kicker passage is uncovered by the piston so that the valve will be thrown forward relatively quickly during the rearward movement .of the piston. The rear end of the piston chamber will, therefore, be charged before the piston has completed itsnominal stroke rearwardly and the piston will then be immediately reversed and actuated on its working stroke.

During this forward movement of the piston and when the annular groove 63 establishes communication between the exhaust passages 60 and El the pressure fluid will be exhausted quickly from the kicker passage and the valve chamber so that the valve may be reversed slightly earlier during the power stroke of the piston and the piston will, in consequence, deliver a comparatively light blow.

We claim:

1. A pressure fluid actuated rock drill, com prising a cylinder having a piston chamber, a piston reciprocable in the piston chamber having a rear pressure surface and a front pressure surface of smaller area than the rear pressure surface, a valve chest having a valve chamber and an exhaust port, an inlet passage leading from the valve chamber to the rear end of thepiston chamber, a pressure fluid supply conduit for the valve chamber, a valve in the valve chamber to communicate the supply conduit with the inlet passage and to control communication between the inlet passage and the exhaust port, means to intermittently convey fluid pressure to and from the piston chamber at a selectively Variable controlled rate of flow to actuate the valve, and means for constantly supplying pressure fluid to the front pressure surface.

2. A pressure fluid actuated rock drill, comprising a cylinder having a piston chamber, a

piston reciprocable in the piston chamber having a rear pressure surface and a front pressure surface of smaller area than the rear pressure surface, a valve chest having a valve chamber and j an exhaust port, an inlet passage leading from the valve chamber to the rear end of the piston chamber, a pressure fluid supply conduit for the valve chamber, a valve in the valve chamber to communicate the supply conduit with the inlet passage and to control communication between the inlet passage and the exhaust port, means to intermittently convey fluid pressure to and from the piston chamber at a selectively variable controlled rate of flow to actuate the valve, means for constantly supplying pressure fluid to the front pressure surface, and a bore in the valve affording constant communication between the supply conduit and the said means.

3. A pressure fluid actuated rock drill, comprising a cylinder having a piston chamber, a piston reciprocable in the piston chamber having a rear pressure surface and a front pressure surface smaller area than the rear pressure surface, a valve chest having a valve chamber and an exhaust port, an inlet passage leading from the valve chamber to the rear end of the piston chamber, a pressure fluid supply conduit for the valve chamber, a valve in the valve chamber to control communication between the supply conduit and the inlet passage and between the inlet passage and the exhaust port, an actuating area on the valve constantly subjected to pressure fluid for throwing the valve in one direction, an actuating surface on the valve intermittently subjected to pressure fluid valved from the front end of the piston chamber by the piston for throwing the valve in the opposite direction, means for controlling the rate of flow of fluid from the front end of the piston chamber to the actuating surface, and means for constantly supplying pressure fluid to the front end of the piston chamber.

4. A pressure fluid actuated rock drill, com- I prising a cylinder having a piston chamber, a piston reciprocable in the piston chamber having a rear pressure surface and a front pressure surface of smaller area than the rear pressure surface, a valve chest having a valve chamber and an exhaust port, an inlet passage leading from the valve chamber to the rear end of the piston chamber, a pressure fluid supply conduit for the valve chamber, a valve in the valve chamber to control communication between the supply conduit and the inlet passage and between the inlet passage and the exhaust port, an actuating area on the valve constantly subjected to pressure fluid for throwing the valve in one direction,

an actuating surface on the valve intermittently subjected to pressure fluid for throwing the valve in the opposite direction, a kicker passage for conveying pressure fluid from the front end of the piston chamber to the actuating surface and being controlled by the piston, valve means for controlling the rate of flow of fluid through the kicker passage to and from the actuating surface, and means for constantly supplying pressure fluid to the front end of the piston chamber.

5. A pressure fluid actuated rock drill, comprising a cylinder having a piston chamber, a piston reciprocable in the piston chamber having a rear pressure surface and a front pressure surface of smaller area than the rear pressure surface, a valve chest having a valve chamber and an exhaust port, an inlet passage leading from the valve chamber to the rear end of the piston chamber, a pressure fluid supply conduit for the valve chamber, a valve in thevalvechamber tocontrol communication between thesupply conduit and the inlet passage and between the inlet passage and the exhaust port, an actuating area on the valve constantly subjected to pressure fluid for throwing the valve in one direction, an actuating surface on the valve intermittently subjected to pressure fluid for throwing the valve in the opposite direction, a kicker passage for conveying pressure fluid from the front end of the piston chamber to the actuating surface and being controlled by the piston, a valve to selectively restrict the flow of pressure fluid from the piston chamber into the kicker passage, and means for constantly supplying pressure fluid to the front end of the piston chamber.

6. A pressure fluid actuated rock drill, comprising a cylinder having a piston chamber, a piston reciprocable in the piston chamber having a rear pressure surface and a front pressure surface of smaller area than the rear pressure surface, a valve chest having a valve chamber and an exhaust port, an inlet passage leading from the valve chamber to the rear end of the piston chamber, a pressure fluid supply conduit for the valve chamber, a valve in the valve chamber to control communication between the supply conduit and the inlet passage and between the inlet passage and the exhaust port, an actuating area on the valve constantly subjected to pressure fluid for throwing the valve in one direction, an actuating surface on the valve intermittently sub jected to pressure fluid for throwing the valve in the opposite direction, a kicker passage for conveying pressure fluid from the front end of the piston chamber to the actuating surface and being controlled by the piston, an exhaust passage for the kicker passage controlled by the piston, a valve for selectively restricting the flow of fluid from the kicker passage to the exhaust passage, and means for constantly supplying pressure fluid to the front end of the piston chamber.

7. A pressure fluid actuated rock drill, comprising a cylinder having a piston chamber, a piston reciprocable in the piston chamber having a rear pressure surface and a front pressure surface of smaller area than the rear pressure surface, a valve chest having a valve chamber and an exhaust port, an inlet passage leading from the valve chamber to the rear end of the piston chamber, a pressure fluid supply conduit for the valve chamber, a valve in the valve chamber to control communication between the supply conduit and the inlet passage and between the inlet passage and the exhaust port, an actuating area on the valve constantly subjected to pressure fluid for throwing the valve in one direction, an-actuating surface on the valve intermittently subjected to pressure fluid for throwing the valve in the opposite direction, a kicker passage for conveying pressure fluid from the front end of the piston chamber to the actuating surface and being controlled by the piston, a valve to selectively restrict the flow of pressure fluid from the piston chamber into the kicker passage, an exhaust passage leading from the kicker passage to the piston chamber, a valve to selectively restrict the flow of fluid from the exhaust passage to the piston chamber, a second exhaust passage affording communication between the piston chamber and the atmosphere, an annular groove in the piston to afford communication between the exhaust passages, and means for constantly supplying pressure fluid to the front end of the piston chamber.

WILLIAM A. MORRISON. ARTHUR D, BENNETT. 

